Mr. McCloskeyMr. McCloskeyBiology IIBiology II

Class MammaliaClass MammaliaMammalsMammals

Threatened and Endangered Threatened and Endangered Species of PASpecies of PA

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MammalsMammals

►Came into being around 200 million Came into being around 200 million years ago – flourished to around 70 years ago – flourished to around 70 million years agomillion years ago

►Although not a large group Although not a large group (approximately 4450 species) it is (approximately 4450 species) it is overall the most biologically overall the most biologically differentiated group in the animal differentiated group in the animal kingdom.kingdom.

MammalsMammals►Mammals probably have been Mammals probably have been

influenced by humans more than any influenced by humans more than any other group of animals.other group of animals.

►Mammals have been domesticated for Mammals have been domesticated for clothing, as beasts of burden, and as clothing, as beasts of burden, and as pets.pets.

MammalsMammals

►Millions used in biomedical research Millions used in biomedical research each year.each year.

MammalsMammals

►Mammals have been introduced into Mammals have been introduced into new habitats (with both positive and new habitats (with both positive and negative results) negative results)

MammalsMammals

►Mammals have led to the destruction Mammals have led to the destruction of habitats for commercial uses.of habitats for commercial uses.

MammalsMammals

►Some animals have been greatly over Some animals have been greatly over harvested.harvested.

CharacteristicsCharacteristics►Body covered with hair (Reduced in Body covered with hair (Reduced in

some species, especially aquatic some species, especially aquatic ones).ones).

Skin with many glandsSkin with many glands

►Sweat glands – not present in any Sweat glands – not present in any other vertebratesother vertebrates

►Scent glands - found in nearly all Scent glands - found in nearly all mammals although functions vary mammals although functions vary greatly. Used by some species for greatly. Used by some species for communication, to mark territory, for communication, to mark territory, for warning and for defense.warning and for defense.

Skin with many glandsSkin with many glands

►Sebaceous glands – sometimes called Sebaceous glands – sometimes called oil glandsoil glands

►Mammary glands – produce milk for Mammary glands – produce milk for nourishing young.nourishing young.

LimbsLimbs

►Four limbs- (reduced or absent in Four limbs- (reduced or absent in some) adapted for many forms of some) adapted for many forms of locomotionlocomotion

HeartHeart

►Four chambered heart with 2 atria and Four chambered heart with 2 atria and 2 ventricles2 ventricles

►Warm bloodedWarm blooded

TeethTeeth

►Well developed teethWell developed teeth►Teeth will be adapted for specific dietTeeth will be adapted for specific diet►4 types of teeth found in mammals4 types of teeth found in mammals

Incisors = Flat, sharp edges, used for Incisors = Flat, sharp edges, used for snipping, cutting and gnawing.snipping, cutting and gnawing.

TeethTeeth

►Canines = long and pointed, used for Canines = long and pointed, used for tearing and piercingtearing and piercing

TeethTeeth

►Premolars = compressed square Premolars = compressed square shape, for shearing and slicingshape, for shearing and slicing

TeethTeeth

►Molars = Large bodies, squared also, Molars = Large bodies, squared also, used for crushing and grindingused for crushing and grinding

TeethTeeth

►Types of teeth present and size will vary Types of teeth present and size will vary according to the animal’s needs.according to the animal’s needs.

►Most mammals grow just two sets of Most mammals grow just two sets of teeth.teeth.

Deciduous teethDeciduous teeth

Permanent teethPermanent teeth

TeethTeeth

►Deciduous teeth Deciduous teeth = (Milk teeth) – = (Milk teeth) – First temporary First temporary set.set.

TeethTeeth

►Permanent teeth Permanent teeth = Grow in when = Grow in when the skull has the skull has grown large grown large enough to enough to accommodate a accommodate a full set (Molars full set (Molars only come in with only come in with other permanents other permanents – not present in – not present in deciduous set)deciduous set)

LungsLungs

►Mammals use lungs to breath for their Mammals use lungs to breath for their entire life.entire life.

Highly Developed BrainsHighly Developed Brains

►Especially well developed in primates.Especially well developed in primates.

3 major regions3 major regions• Cerebrum – Largest portion, controls Cerebrum – Largest portion, controls

voluntary functionsvoluntary functions• Cerebellum – Balance, involuntary Cerebellum – Balance, involuntary

actions, muscle coordinationactions, muscle coordination• Medulla oblongata – vital body processes Medulla oblongata – vital body processes

such as breathing and heart beatsuch as breathing and heart beat

3 Lines of Mammal 3 Lines of Mammal DevelopmentDevelopment

►1) Monotremes1) Monotremes►Egg-laying mammals – mothers have Egg-laying mammals – mothers have

no nipplesno nipples►Only 3 species exist – Duck-billed Only 3 species exist – Duck-billed

Platypus and 2 spiny AnteatersPlatypus and 2 spiny Anteaters►They live in Australia, New Guinea and They live in Australia, New Guinea and

TasmaniaTasmania

MarsupialsMarsupials►MarsupialsMarsupials►Pouched mammalsPouched mammals►Give birth to tiny young which are Give birth to tiny young which are

effectively still embryos both effectively still embryos both anatomically and physiologicallyanatomically and physiologically

►Must crawl to mother’s pouch to Must crawl to mother’s pouch to complete developmentcomplete development

►Found mainly in Australia, opossum is Found mainly in Australia, opossum is the only native North American the only native North American speciesspecies

Placental MammalsPlacental Mammals►Most highly evolved animals on EarthMost highly evolved animals on Earth►Carry unborn young in the uterus – Carry unborn young in the uterus –

nourished by the placentanourished by the placenta►Materials transferred from mother to Materials transferred from mother to

unborn young through the umbilical cordunborn young through the umbilical cord►The period of time that young develops The period of time that young develops

in placenta is called the Gestation Period in placenta is called the Gestation Period – This will vary from mammal to – This will vary from mammal to mammal mammal

►(Mouse – 21 days, rabbit 30-60 days, (Mouse – 21 days, rabbit 30-60 days, horse – 48 weeks, elephant 22 months)horse – 48 weeks, elephant 22 months)

Threatened or Endangered Threatened or Endangered SpeciesSpecies

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